Clemens, in U.S. Pat. No. 3,842,194, has disclosed a system for recording and playback of information, including audio, video and color information, capacitively. The high density information record has signal information in the form of a surface relief pattern in an information track, e.g., a spiral groove, on the surface of the record. The record is made conductive with a metal layer, which acts as the first electrode of a capacitor, and then with a dielectric layer. The record is played back by means of a stylus electrode which is the second electrode of the capacitor. Since the record is rotated at a fairly high speed, on the order of 450 rpm, the friction between the stylus and the record surface may result in undue stylus wear. Thus, a lubricant is applied to the surface of the record.
A suitable class of lubricants has been described by Matthies in U.S. Pat. No. 3,833,408, herein incorporated by reference. These lubricants have the generic formula ##STR1## wherein R is an alkyl group of 4 to 20 carbon atoms and n is an integer.
Various improvements have been made to the record of Clemens including a record made from a conductive plastic which avoids the need for applying separate conductive metal and dielectric layers. Such a record may contain conductive particles for example. Improvement has also been made to the lubricant system. It has been found that when the lubricant is purified and fractionated, improved playback and storage stability results. The fractionated lubricant has the formula ##STR2## wherein R.sub.1 and R.sub.2 are alkyl groups of 4-20 carbon atoms, x is an integer of 2-4 and y is an integer of 0-2 and wherein the sum of x and y is 4 or less. The improved lubricant has better long term stability and improved first play performance and is described in U.S. Pat. No. 4,275,101 and also is herein incorporated by reference.
In an effort to still further improve the performance of video records, particularly to improve the resistance of the records to degradation from the effects of high temperatures and high relative humidity, the fractionated lubricant has been doped with several types of amines or quaternary ammonium salts, or silicon compounds. For example, Datta et al have disclosed the addition of hydroxylated amines to the fractionated lubricant to improve stability to moisture in copending application Ser. No. 231,857 filed Feb. 5, 1981 now U.S. Pat. No. 4,330,583; Wang et al have disclosed the addition of hydroxylated methylalkyldisiloxanes to the fractionated lubricant in copending application Ser. No. 231,859 filed Feb. 5, 1981, now U.S. Pat. No. 4,355,062; and Preston has disclosed the addition of an amino silane to the fractionated lubricant in copending application Ser. No. 231,750 also filed Feb. 5, 1981 now U.S. Pat. No. 4,327,140. Other dopants are also known.
The above doped lubricants perform excellently on the surface of the high density information records, but particularly well on those records which have been cleaned in aqueous solutions. It would be highly desirable to be able to provide lubricant systems that impart commercial quality readout for records exposed to a variety of environments without the need for precleaning the surface to remove contaminants.